The present invention is generally directed to a communication system and method of a vehicle occupant protection system. Specifically, the present invention is directed to communication within a distributed protection system.
As the sophistication of vehicle occupant protection systems has increased, the number and complexity of vehicle occupant protection devices within the protection systems has increased. In response to the increased number of devices, there has been a movement toward centralized information processing and/or control of the devices within the protection systems to reduce cost and increase reliability. This change in the design approach for protection systems has brought about a need to design new arrangements for communication.
In one known type of system, a communication bus interconnects a central unit and a plurality of remote units. Electric signals pass through the communication bus. However, under certain conditions, the electric signals create unwanted radio frequency emissions that permeate areas adjacent to the communication bus.
In accordance with one aspect, the present invention provides a communication system. The system includes an electrical conductor that interconnects a plurality of units for conducting electrical energy. Energy supply means provides electrical energy, which has a voltage, onto the conductor. Voltage messaging means modulates the voltage to convey messages from a first unit to a second unit via the conductor. Voltage receiver means monitors the voltage of the electrical energy to discern messages from the first unit. The voltage messaging means includes means for adjusting the voltage of the electrical energy past a first predetermined threshold to provide a first type message frame and for modulating the voltage of the electrical energy during the first type message frame to convey a first type message. The voltage messaging means includes means for adjusting the voltage of the electrical energy past a second predetermined threshold to provide a second type message frame and for modulating the voltage of the electrical energy during the second type message frame to convey a second type message.
In accordance with another aspect, the present invention provides an occupant protection system for protecting a vehicle occupant. The system includes an actuatable occupant protection device for protecting the vehicle occupant. A central unit controls actuation of the protection device and provides power for use by the protection device. The protection device is located remote from the central unit. An electrical conductor interconnects the central unit and the protection device for conducting electrical energy. The central unit includes energy supply means for providing electrical energy, that has a voltage, onto the conductor and includes voltage messaging means for modulating the voltage to convey messages from the central unit to the protection device. The protection device includes voltage receiver means for monitoring the voltage of the electrical energy to discern messages from the central unit. The voltage messaging means includes means for adjusting the voltage of the electrical energy past a first predetermined threshold to provide a first type message frame and for modulating the voltage of the electrical energy during the first type message frame to convey a first type message. The voltage messaging means includes means for adjusting the voltage of the electrical energy past a second predetermined threshold to provide a second type message frame and for modulating the voltage of the electrical energy during the second type message frame to convey a second type message.
In accordance with another aspect, the present invention provides a method of communicating between a plurality of units. Electrical energy, that has a voltage, is provided onto a conductor that interconnects the units. The voltage of the electrical energy is adjusted past a first predetermined threshold to provide a first type message frame from a first unit. The voltage of the electrical energy is modulated during the first type message frame to convey a first type message from the first unit to the second unit. The voltage of the electrical energy is adjusted past a second predetermined threshold to provide a second type message frame from the first unit. The voltage of the electrical energy is modulated during the second type message frame to convey a second type message from the first unit to the second unit. The voltage of the electrical energy is monitored at the second unit to discern the message frames and the messages from the first unit.